Quinolone-resistant Haemophilus influenzae in a long-term care facility: clinical and molecular epidemiology

Clin Infect Dis. 2004 Jun 1;38(11):1564-9. doi: 10.1086/420820. Epub 2004 May 12.


We describe a clonal outbreak of quinolone-resistant Haemophilus influenzae (QRHI) from an affiliated long-term care facility (LTCF-A); the outbreak was associated with the clinical use of levofloxacin, which was determined to be a risk factor for acquisition of QRHI. The minimum inhibitory concentration to which 90% of isolates were susceptible (MIC90), as determined by broth microdilution, was >4 microg/mL for levofloxacin, >2 microg/mL for moxifloxacin, >2 microg/mL for gatifloxacin, and 8 microg/mL for gemifloxacin. The MIC90, as determined by Etest (AB Biodisk), was >32 microg/mL for levofloxacin, ciprofloxacin, moxifloxacin, and gatifloxacin. Having been a resident at LTCF-A and having chronic obstructive pulmonary disease were significant risk factors for acquisition of QRHI at our 500-bed hospital (New York Hospital Queens). All QRHI isolates were found to be genetically related by pulsed-field gel electrophoresis, were nontypeable, were susceptible to ceftriaxone and azithromycin, and were negative for beta -lactamase production. Emphasis on patient contact and respiratory isolation and placing colonized or infected patients in cohorts yielded a marked reduction in the prevalence of QRHI at LTCF-A.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Anti-Infective Agents / metabolism
  • Anti-Infective Agents / therapeutic use
  • Case-Control Studies
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial / genetics*
  • Electrophoresis, Gel, Pulsed-Field / methods
  • Electrophoresis, Gel, Pulsed-Field / statistics & numerical data
  • Female
  • Haemophilus Infections / epidemiology*
  • Haemophilus Infections / genetics*
  • Haemophilus Infections / prevention & control
  • Haemophilus Infections / transmission
  • Haemophilus influenzae / drug effects*
  • Haemophilus influenzae / genetics*
  • Haemophilus influenzae / isolation & purification
  • Humans
  • Infection Control / methods
  • Infection Control / statistics & numerical data
  • Inhibitory Concentration 50
  • Levofloxacin*
  • Long-Term Care / trends*
  • Male
  • Microbial Sensitivity Tests / methods
  • Microbial Sensitivity Tests / statistics & numerical data
  • Molecular Epidemiology / methods*
  • Multivariate Analysis
  • Ofloxacin / metabolism*
  • Ofloxacin / therapeutic use
  • Sex Factors


  • Anti-Infective Agents
  • DNA, Bacterial
  • Levofloxacin
  • Ofloxacin